| 摘要 |
A method of applying a conductive carbon coating to a non-conductive layer, conductive carbon compositions, and a printed wiring board having through holes or other surfaces treated with such carbon compositions are disclosed. A board or other substrate including at least first and second electrically conductive metal layers separated by a non-conductive layer is provided. The board has a recess extending through at least one of the metal layers into the non-conductive layer. The recess has a non-conductive surface which is desired to be made electrically conductive. The carbon in the dispersion has a mean particle size no greater than about 50 microns. The method is carried out by applying the carbon dispersion to a non-conductive surface of the recess to form a substantially continuous, electrically conductive carbon coating. Optionally, the coating is then fixed, leaving the carbon deposit as a substantially continuous, electrically conductive layer. Chemical and physical fixing steps are disclosed. The resulting coating has a low electrical resistance and is tenacious enough to be plated and exposed to molten solder without creating voids or losing adhesion.
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